Augmented reality is a technology by which computer graphic (CG) made by computer coexists with a real world to enable users to feel like the computer graphic exists in the real world. In augmented reality, virtual environment made by a computer is used to supplement the real world with a virtual world, but the main part is the real environment. In other words, it provides information required for the real environment by overlapping 3-dimensional images with a real image the user is watching.
Meanwhile, a degree of accuracy is required for medical operation of a doctor on a patient and the doctor is required to be capable of monitoring the current status during surgery. Especially in case of brain surgery, it is necessary to actively secure sight of seeing the surgeon wishes, but the current surgical system is not enough to solve to this problem.
A navigation system and the like, thus, are used for solving this problem. While the conventional surgical method relies on doctor's experiences, the navigation surgery is highly accurate because it has undergone a verification procedure through a computer.
However, the navigation system cannot achieve effective display alone. In other words, most of obtained images are 2-dimensional images which require lots of experiences and judgments of doctors, and such information which relies on operator's imagination may cause mistakes or difficulty in accurate operation.
Recently, thus, in order to improve operation accuracy, augmented reality that displays patient's image like CT (computer tomography) or MRI (magnetic resonance imaging) with being overlapped with image captured by camera is applied to the navigation system.
In this case, the more accurate augmented reality can be achieved only when adjustment of coordinate of an optical center of the camera is done.
FIG. 1 is a diagram explaining the conventional method of adjusting coordinate of an optical center of a camera.
Referring to FIG. 1, for adjusting the optical center of the camera 120, after the operator manually stamped a tool to which the marker 140 is attached on a pattern board 130, it is performed to track the marker 140 attached on the camera 120 and the marker 140 attached on the tool via optical tracker 110 of the navigation system to detect a coordinate Opp of the marker 140 attached on the camera 120 and a coordinate Opp of the marker 140 attached on the tool. Then, a coordinate Oc of an optical center of the camera 120 is calculated by using the coordinate Opp of the marker 140 attached on the camera 120 and the coordinate Ocm of the marker 140 attached on the tool, and a position and an orientation of the optical center of the camera is adjusted by a processor (not shown).
However, as described above, the conventional method of calculating a distance between an optical center of a camera 120 has a problem that an error range of an augmented reality becomes bigger since a coordinate Opp of a marker 140 attached on a tool is calculated by manually stamping the tool, which is attached on the marker 140, on a pattern board 130.
In other words, an error range of an augmented reality is large since it is not possible to stamp accurately every time a tool, on which a marker 140 is attached, on the pattern board 130 to a coordinate system direction by manually, and as well as, an error range of an augmented reality becomes larger since an error is accumulated by calculating a spatial coordinate of a marker 140 according to each position of a tool on which the marker 140 is attached, the maker 140 is attached on the tool stamped on a pattern board several times with different positions.
In addition, since the tool is manually stamped on the pattern board 130, therefore, single person is impossible to do the work.